the definition of tourism value chain based on tourists' needs. The demand of tourists drives the formation of tourism industry elements, so the definition of tourism industry chain is often based on the demand of tourists. For example, Li Danfeng and others believe that the tourism industry chain refers to an industrial link relationship formed by the enterprises involved in tourism consumption, such as eating, living, traveling, traveling, entertainment, shopping, etc., in the process of a series of activities from obtaining tourism information and deciding to travel, moving through space, and finally realizing tourism experience (Li Danfeng Qin Qiao & Zhang Lin, 2119). He Jianmin pointed out that for conventional tourism, the tourism value chain includes target customer selection, positioning, product design, price setting, channel selection and image promotion (He Jianmin, 2117). These concepts all emphasize that the industrial chain begins with the spatial movement of tourists and ends with the realization of tourists' tourism consumption experience. It is a collection of related enterprises with six elements: food, housing, transportation, travel, shopping and entertainment. This definition method makes the boundary of tourism industry relatively narrow, which is usually called narrow tourism industry, but it is convenient for statistics and operation. For this reason, the statistical caliber of tourism industry led by the National Tourism Administration basically adopts this definition.

the definition of tourism value chain based on the supply of tourism products. Generally speaking, tourism industry is composed of a collection of tourism enterprises that produce tourism products and services, so many definitions of tourism industrial chain start from the perspective of the supply of tourism products and services, such as Tapper and Font, which define tourism industrial chain as a chain that includes the supply and distribution of all tourism products and services (Tapper &; Font, 2114), the tourism value chain can therefore be divided into four stages: win order, pre-delivery support, delivery and post-delivery support, so as to realize seamless end-to-end connection of tourism products (Yilmaz &: Bititci, 2116), or the tourism industry chain is defined as a single chain (KaukalH? pken & Werthner, 2112)。

the definition of tourism value chain based on the supply of tourism products within the scope of spatial movement. The definition of tourism industry chain based on tourists' demand divides the starting point and the end point of tourism industry chain, which makes the research of tourism industry operable. The value chain based on the supply of tourism products and services emphasizes the diversity of tourism industry chain, but it is caught in the dilemma of concept generalization. Therefore, some scholars limit the end point of the value chain of tourism products and services to "the distribution and marketing of specific tourist destinations", and the corresponding tourism supply value chain is defined as: "a network of tourism organizations that participate in different activities from the supply of different parts of tourism products/services (such as aviation industry and accommodation industry) to the distribution and marketing of final tourism products in specific tourist destinations (ZhangSong & Huang, 2119)”。 Or limit the tourism supply to the process of tourists' spatial transfer, such as "processing, combining and providing tourism products for tourists in the process of spatial transfer and tourism consumption to help them complete their travel and sightseeing to their destinations, and the supply-demand relationship of various industries with tourism enterprises as the core formed here (Wang Baolun & Cassie Wang, 2116) "